Showing papers by "James Dziura published in 2003"
TL;DR: Elderly study participants were markedly insulin-resistant as compared with young controls, and this resistance was attributable to reduced insulin-stimulated muscle glucose metabolism, which supports the hypothesis that an age-associated decline in mitochondrial function contributes to insulin resistance in the elderly.
Abstract: Insulin resistance is a major factor in the pathogenesis of type 2 diabetes in the elderly. To investigate how insulin resistance arises, we studied healthy, lean, elderly and young participants matched for lean body mass and fat mass. Elderly study participants were markedly insulin-resistant as compared with young controls, and this resistance was attributable to reduced insulin-stimulated muscle glucose metabolism. These changes were associated with increased fat accumulation in muscle and liver tissue assessed by 1H nuclear magnetic resonance (NMR) spectroscopy, and with a approximately 40% reduction in mitochondrial oxidative and phosphorylation activity, as assessed by in vivo 13C/31P NMR spectroscopy. These data support the hypothesis that an age-associated decline in mitochondrial function contributes to insulin resistance in the elderly.
1,984 citations
TL;DR: In obese children and adolescents with prediabetes, intramyocellular and intra-abdominal lipid accumulation is closely linked to the development of severe peripheral insulin resistance.
489 citations
TL;DR: Plasma adiponectin levels are reduced in adolescent obesity and related to insulin resistance, independent of total body fat and central adiposity, and there is a strong relationship between adip onectin and IMCL lipid content in this pediatric population.
Abstract: We examined the impact of adolescent obesity on circulating adiponectin levels and the relationship between adiponectin and insulin sensitivity, intramyocellular (IMCL) lipid content, plasma triglycerides, and free fatty acids. Plasma adiponectin levels were measured in 8 nonobese (percentage fat, 18 +/- 1.8) and 14 obese adolescents (percentage fat, 41 +/- 1.6). Insulin sensitivity was assessed by the euglycemic-hyperinsulinemic clamp. Intramuscular lipid content was quantified using (1)H-nuclear magnetic resonance spectroscopy, and abdominal fat distribution by magnetic resonance imaging. Adiponectin levels were lower in obese adolescents (9.2 +/- 1 microg/ml, P < 0.001) and were positively related to insulin sensitivity in all subjects (r = 0.531, P < 0.02). Strong inverse relationships were found between adiponectin and triglyceride levels (r = -0.80, P < 0.001) and IMCL (r = -0.73, P < 0.001). Triglycerides (partial r(2) = 0.52; P < 0.0002) and IMCL (partial r(2) = 0.10; P < 0.05) were the most significant predictors of adiponectin levels, explaining 62% of the variation. In conclusion, plasma adiponectin levels are reduced in adolescent obesity and related to insulin resistance, independent of total body fat and central adiposity. There is a strong relationship between adiponectin and IMCL lipid content in this pediatric population. The putative modulatory effects of adiponectin on insulin sensitivity may, in part, be mediated via its effects on IMCL lipid content.
212 citations